1. Field of the Invention
The invention pertains to a working method and to an installation for the flexible and economical pickling and cold-rolling of metal strip, especially in small-to-medium production volumes on an installation consisting of an in-line arrangement of a metal pickler, a reeling arrangement on the coiling side of the metal pickler, and a cold-rolling mill.
2. Description of the Related Art
It is known that metal picklers and rolling mills can be connected and operated as so-called xe2x80x9cendless rolling millsxe2x80x9d. These mill layouts offer many advantages because of the elimination of the discontinuous threading operation, and they usually provide very high production rates per unit time. They require such a large investment, however, that many operators of installations for smaller production volumes continue to invest in separate metal picklers and rolling mills.
In order to achieve higher production rates in spite of this difficulty, multi-stand reversing mills and/or the creation of extremely large coils only for the section between the metal pickler and the mill have been proposed, these large coils being uncoiled and cut downline from the mill so that they are small enough to be transported and subjected to further processing (U.S. Pat. No. 5,495,736). Installations of this type require extremely large custom equipment for the coiling machines, which appears to cast doubt on the cost advantages.
The task of the present invention is to create a process and an installation by means of which an extremely flexible pickling-and-rolling operation for small-to-medium production volumes can be achieved economically without the need to add or omit any system components for operational reasons, with minimal investment and personnel costs, and with the use of conventional coil sizes and machine dimensions.
To accomplish this task with the use of a given installation consisting of an in-line arrangement of a metal pickler, a reeling arrangement on the coiling side of the metal pickler, and a cold-rolling mill, a working method is proposed which is characterized by various alternative sequences of work steps:
(a) the strip leaving the metal pickler bypasses the reeling arrangement and is introduced into the cold-rolling mill for a first reduction pass and rolled out over the course of several deformation passes; or
(b) the strip leaving the metal pickler is wound on the reeling arrangement into a coil; after the coil is switched to the uncoiling position, the strip is fed into the cold-rolling mill and rolled out over the course of several deformation passes; or
(c) the strip leaving the metal pickler is wound as hot-rolled strip on the reeling arrangement to obtain the finished strip; or
(d) pre-pickled, hot-rolled strips are sent to the reeling arrangement and then uncoiled from the uncoiler into the cold-rolling mill and rolled in several deformation passes.
In the solution proposed according to the invention, a so-called xe2x80x9cpartial couplingxe2x80x9d of a metal pickler and rolling mill is set up in a consistent manner so that all three operating modes, i.e., endless rolling, partial coupling, and discontinuous operation, can be run equally well on one and the same installation.
In accordance with an embodiment of the invention, it is preferably provided that the cold-rolling is done on a reversing mill into which the strip produced according to work step (a), (b), or (c) is introduced and rolled out over the course of several reversing passes, where the strip, after one or more reversing passes, is wound on at least one of the reversing reels, one of which is installed at each end of the reversing mill.
According to another feature of the invention, it is also an effective option to cold-roll the strip produced according to work step (a), (b), or (d) on a 2-stand or 3-stand tandem line, on which the strip, is rolled out in a single pass, or, in accordance with another alternative, to wind the strip after one or more reversing passes on at least one of the two reversing reels, one of which is installed at each end of the tandem line.
An installation for the flexible and economical pickling and cold-rolling of metal strip according to the work steps defined according to the invention is characterized by a reeling arrangement, which is designed as a horizontal or vertical reverse coiler with two separate drive units, one for each reel mandrel, these drives preferably being disconnected when the reeling arrangement is reversed. Layouts of this type are known in principle; only its inclusion in the complete installation according to the invention for performing all of the work steps in question is claimed by the present invention.
It is favorable for the reel mandrels of the reverse coiler to be free to move in the axial direction in their housings, so that, as the coil is being fed out from the reel mandrel downstream from the metal pickler, it can be kept centered as it enters the rolling mill.
The reversing mill can be designed as a conventional reversing stand or as a 2-stand or 3-stand tandem group with a reversing reel installed at each end of the tandem group. As soon as the reversing reel of the reversing stand has accepted the strip, the reel mandrel of the reverse coiler is free again to form a new coil from the strip coming from the metal pickler.
Especially when high pass reductions are required, e.g., when rolling is performed in only a single pass, it is favorable for the cold-rolling mill to be equipped with 6-high stands, which allow a greater degree of deformation.
An installation according to the invention for implementing the working method is extremely flexible, needs only a minimum of operating personnel, requires little room, has low investment costs, and shows its greatest economy in conjunction with the use of the thin, hot-rolled strip which is being produced increasingly in thin slab plants and strip-casting plants.